Inter-individual and inter-cell type variation in residual DNA damage after in vivo irradiation of human skin

Abstract Purpose The aim of this study was to compare inter-individual and inter-cell type variation in DNA double-strand break (DSB) repair following in vivo irradiation of human skin. Materials and methods Duplicate 4 mm core biopsies of irradiated and unirradiated skin were collected from 35 patients 24 h after 4 Gy exposure using 6 MeV electrons. Residual DSB were quantified by scoring 53BP1 foci in dermal fibroblasts, endothelial cells, superficial keratinocytes and basal epidermal cells. Results Coefficients of inter-individual variation for levels of residual foci 24 h after in vivo irradiation of skin were 39.9% in dermal fibroblasts, 44.3% in endothelial cells, 32.9% in superficial keratinocytes and 46.4% in basal epidermal cells ( p p  = 0.034, ANOVA). Foci levels between the different skin cell types were correlated (Pearson’s R  = 0.855–0.955, p Conclusions Patient-specific factors appear to be more important than cell type-specific factors in determining residual foci levels following in vivo irradiation of human skin.